This represents continuation of our research program which is aimed at elucidation of the developmental aspects of the neurohumoral control of the fetal and neonatal circulation, as well as the various factors that control the uteroplacental circulation in health and disease. Specifically, the following subjects will be investigated: 1) intrinsic and neurogenic control of fetal circulation throughout intrauterine life and the changes that occur throughout the neonatal period until adult pattern; 2) in vivo and in vitro responses of the various vascular structures to neurohumoral stimuli; 3) behavior of the cardiovascular system of the fetus, neonate and adult following chemical sympathectomy during stressful conditions.